package bTree.LeetCode;

public class 不同的子序列 {
    public int numDistinct(String s, String t) {
        int length1 = s.length();
        int length2 = t.length();
        int [][]dp=new int[length1+1][length2+1];
        for (int i = 0; i < length2; i++) {
            dp[0][i]=0;
        }
        for (int i = 0; i < length1; i++) {
            dp[i][0]=1;
        }
        dp[0][0]=1;
        for(int i=1;i<=length1;i++){
            for(int j=1;j<=length2;j++){
                if(s.charAt(i-1)==t.charAt(j-1)){
                    dp[i][j]=dp[i-1][j-1]+dp[i-1][j];
                }else{
                    dp[i][j]=dp[i-1][j];
                }
            }
        }
        return dp[length1][length2];
    }
}
